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62 lines
1.4 KiB
62 lines
1.4 KiB
#include "ringbuf_small.h"
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#include <util/atomic.h>
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/* Very generic implementation of an interrupt-safe ringbuffer
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*
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* Contention handling:
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* - writing of pointers only with interrupt lock
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* - reading of pointers allowed at any time
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* - volatile not really necessary, unless you really need the functions to
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* react to freespace/newdata while they're running
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*
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* PUT AND GET ARE NOT REENTRANT!
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*/
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void ringbuf_init(ringbuf_t *rb, uint16_t *buf, uint8_t size){
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rb->startptr = buf;
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rb->size = size;
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rb->readpos = 0;
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rb->writepos = 0;
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}
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/* pushes a value onto the ringbuffer
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* returns 0 on success, 1 on buffer full
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*/
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uint8_t ringbuf_put(ringbuf_t *rb, uint16_t value){
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// calculate next ptr pos
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uint8_t next = rb->writepos + 1;
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if(next >= rb->size){
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next = 0;
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}
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// check for space
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if(next == rb->readpos){
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return(1); // give up
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}
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*(rb->startptr + rb->writepos) = value;
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// do we need a barrier here?
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rb->writepos = next;
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return(0);
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}
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/* gets a value from the ringbuffer
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* returns 0 on success, 1 on buffer empty
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*/
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uint8_t ringbuf_get(ringbuf_t *rb, uint16_t *data){
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//uint16_t value;
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uint8_t next;
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// calculate next ptr pos
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next = rb->readpos + 1;
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if(next >= rb->size){
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next = 0;
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}
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//check for empty
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if(rb->readpos == rb->writepos){
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return(1);
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}
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*data = *(rb->startptr + rb->readpos);
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rb->readpos = next;
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return(0);
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}
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